What are the Anatomical Facts and Safe Filling Techniques in Lip Aesthetics?


The lips are one of the most striking structures in facial aesthetics. Their role in both youthfulness and dynamism, as well as in attractiveness, is undeniable. In various cultures, full, balanced lips have always been considered ideal. However, the aging process, genetic factors, and environmental influences can alter the lip structure. These changes include thinning, loss of lip definition, flattening of the philtrum, and downturned corners of the mouth.

In recent years, interest in minimally invasive aesthetic procedures has increased to correct these changes and restore a youthful appearance to the lips. Hyaluronic acid (HA)-based dermal fillers, in particular, have become the gold standard in lip aesthetics thanks to their biocompatible structure and natural-looking results. However, a thorough understanding of the anatomical structure of the lips is essential for achieving successful results with filler procedures.

The Aesthetic Importance of Lips and Aging-Related Changes
The shape and volume of the lips directly impact the perceived age of the face.

Youthful lips: Full, elastic, and have clear contours.

Aging lips: Loss of volume, blurred lip corners, lengthening of the philtrum, and downward slanting of the mouth corners lead to a more tired appearance.

Histologically, with aging, the collagen and elastin fibers in the lips decrease, the orbicularis oris muscle atrophies, and the lips become thinner. Therefore, filler applications in older individuals not only add volume but also enhance tissue quality, resulting in a youthful expression.

Basic Elements of Lip Anatomy
The lips are multilayered structures composed of skin, muscle, and mucosa. Aesthetically critical points include:

Vermilion border: The distinct line between the lip and normal skin. It is one of the most important areas determining fullness and contour in lip aesthetics.

Cupid's bow: The double fold in the center of the upper lip is considered a symbol of attractiveness.

Philtrum: The vertical groove extending from the base of the nose to the border of the upper lip. It flattens and lengthens with aging.

Commissures: The junctions of the lip corners. They curve downward with aging, creating a tired expression.

In addition to these anatomical structures in the external appearance of the lips, the course of the labial arteries is the most important factor determining the safety of filler applications.

Vascular Anatomy of the Lips
The vessels that supply blood to the lips are the upper and lower labial arteries, which branch from the facial artery.

Superior labial artery: Runs along the upper lip, usually between the mucosa and the orbicularis oris muscle.

Inferior labial artery: Supplies blood to the lower lip, running closer to the alveolar margin.

Labiomental artery: Runs along the crease between the lower lip and the chin and, in some individuals, supplies the entire lower lip.

According to cadaver studies, the most common layer where the labial arteries are found is the submucosal plane. Less commonly, they are intramuscular and, very rarely, subcutaneous. This anatomical variability necessitates the preference for superficial lip filler procedures to reduce the risk of intravenous injection.

Lip Proportions and Cultural Differences
Ideal lip proportions may vary across cultures:

Individuals of African descent: Thicker and wider lips are common.

Individuals of Caucasian descent: The upper lip is slightly thicker and has distinct contours.

Individuals of Asian descent: Thinner lips and different upper-lower lip ratios are seen.

The generally accepted upper-lower lip ratio is 1:1.6. When viewed from a profile, the optimal aesthetic appearance is considered for the upper lip to be approximately 2 mm further forward than the lower lip.

Areas of Lip Augmentation
Patients' reasons for undergoing lip augmentation vary:

In young individuals: The goal is to increase volume, define contours, and achieve a more attractive appearance.

In mature individuals: The goal is to address volume loss due to aging, to lift the lip corners, and to create a more youthful expression.

Fillers are most commonly applied to enhance the vermilion border, Cupid's bow, and lip volume.

Anatomical Considerations in Filling Procedures
Upper lip fillers: Attention should be paid to the course of the superior labial artery, and injections should be superficial.

Lower lip fillers: Consider the labiomental artery and inferior labial artery, and avoid deep injections near the corners of the mouth.

Safest Points: Superficial injections less than 4 mm at the vermilion border reduce the risk of complications.

Using a Cannula: Carries a lower risk of vascular injury than needles.

New Approaches to Safe Filling
Traditionally performed with 13 mm needles increases the risk of vascular injury. One technique recommended in current literature is superficial injections with shorter 4 mm needles.